This invention relates to synthetic lubricants and more particularly to synthetic lubricants prepared from alpha-monoolefins.
It has long been know that synthetic lubricants having superior viscosity and stability properties can be prepared by the controlled polymerization of alpha-monoolefins. For example, U.S. Pat. Nos. 2,500,163, 2,937,129, 3,382,291 and 3,769,363 disclose the preparation of synthetic lubricants by the polymerization of alpha-monoolefins containing about 5 to 18 carbon atoms. Even though such synthetic lubricants have good viscosity and oxidation stability properties they have not been commercially available until recently because they are considerably more expensive to manufacture than conventional lubricants. Increasing demand for high quality lubricants for fuel efficient engines over the last few years has led to the commercialization of such synthetic lubricants. The most commercially successful synthetic lubricants are those prepared from higher alpha-olefins, particularly those having having about 8 to 12 carbon atoms. These olefins are polymerized under conditions such that the resulting polymer is comprised substantially of trimers and tetramers of the alpha-monoolefin. These polymers have good viscosity characteristics, however, the monomers from which they are produced are in relatively short supply and hence they are costly. Attempts have been made to prepare olefin-based synthetic lubricants from the more widely available and less expensive lower alpha-olefins. For example, the preparation of synthetic lubricants from lower alpha-monoolefins, including butene-1, has been reported in U.S. Pat. Nos. 2,357,926 and 2,631,176. Synthetic lubricants made from these materials are less desirable than synthetic lubricants prepared from the higher alpha-olefins since they generally have a wide molecular weight distribution and thus a smaller percentage of product is in the stable, low viscosity lubricating oil range.
The preparation of synthetic lubricants by the copolymerization of mixtures of lower and higher alpha-olefins has been disclosed in U.S. Pat. No. 2,500,162 but these polymers are generally obtained in low yield and are less desirable as synthetic lubricants because they, too, have a wide molecular weight range due to the different polymerization rates of the lower and higher alpha-olefins.
A process has now been developed for the preparation of high quality, less expensive synthetic lubricants which avoids the above-mentioned drawbacks.
Accordingly, it is an object of the invention to present a new process for the preparation of synthetic lubricants. It is another object of the invention to present new synthetic lubricants which have superior viscosity and oxidation stability properties. It is another object of the invention to present superior synthetic lubricants derived from butene-1. It is another object of the invention to present a process for preparing synthetic lubricants from butene-1. It is another object of the invention to present a process for producing copolymers of butene-1 and higher alpha-monoolefin in high yields and having good lubricating oil properties. These and other objects of the invention will become more apparent from the following description of the invention.